The invention relates to a composition for the oxidation dyeing of keratin fibres, and in particular human keratin fibres such as the hair, comprising, in a medium which is suitable for dyeing, at least one oxidation base, at least one C4-C8 ether of a C2 glycol and/or at least one C1-C8 ether of C3-C9 glycol and at least one enzyme of 2-electron oxidoreductase type in the presence of at least one donor for the said enzyme, and to the dyeing process using this composition.
It is known to dye keratin fibres, and in particular human hair, with dye compositions containing oxidation dye precursors, in particular ortho- or para-phenylenediamines, ortho- or para-aminophenols and heterocyclic bases, which are generally referred to as oxidation bases. Oxidation dye precursors, or oxidation bases, are colourless or weakly coloured compounds which, when combined with oxidizing products, can give rise to coloured compounds and dyes by a process of oxidative condensation.
It is also known that the shades obtained with these oxidation bases can be varied by combining them with couplers or colour modifiers, the latter being chosen in particular from aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds.
The variety of molecules used as oxidation bases and couplers allows a wide range of colours to be obtained.
The so-called xe2x80x9cpermanentxe2x80x9d coloration obtained by means of these oxidation dyes must moreover satisfy a certain number of requirements. Thus, it must have no toxicological drawbacks, it must be able to give shades of the desired intensity and it must be able to withstand external agents (light, bad weather, washing, permanent-waving, perspiration, rubbing).
The dyes must also be able to cover white hair and, lastly, they must be as unselective as possible, i.e. they must give the smallest possible colour differences along the same length of keratin fibre, which may in fact be differently sensitized (i.e. damaged) between its tip and its root.
The oxidation dyeing of keratin fibres is generally carried out in alkaline medium, in the presence of hydrogen peroxide. However, the use of alkaline media in the presence of hydrogen peroxide have the drawback of causing appreciable degradation of the fibres, as well as considerable bleaching of the keratin fibres, which is not always desirable.
The oxidation dyeing of keratin fibres can also be carried out using oxidizing systems other than hydrogen peroxide, such as enzymatic systems. Thus, it has already been proposed to dye keratin fibres, in particular in patent application EP-A-0,310,675, with compositions comprising an oxidation base and optionally a coupler, in combination with enzymes such as pyranose oxidase, glucose oxidase or uricase, in the presence of a donor for the said enzymes. Although being used under conditions which do not result in a degradation of the keratin fibres which is comparable to that caused by the dyes used in the presence of hydrogen peroxide, these dyeing processes nevertheless lead to colorations which are not entirely satisfactory, in particular as regards their intensity and resistance to the various attacking factors to which the hair may be subjected.
The Applicant has now discovered that it is possible to obtain new dyes, which are capable of leading to intense and chromatic colorations, without giving rise to any significant degradation of the keratin fibres, and which are relatively unselective and show good resistance to the various attacking factors to which the hair may be subjected, by combining at least one oxidation base, at least one C4-C8 ether of a C2 glycol and/or at least one C1-C8 ether of C3-C9 glycol and at least one enzyme of 2-electron oxidoreductase type in the presence of at least one donor for the said enzyme.
This discovery forms the basis of the present invention.
A first subject of the invention is thus a ready-to-use composition for the oxidation dyeing of keratin fibres, and in particular human keratin fibres such as the hair, characterized in that it comprises, in a medium which is suitable for dyeing:
at least one oxidation base,
at least one C4-C8 ether of a C2 glycol and/or at least one C1-C8 ether of C3-C9 glycol,
at least one enzyme of 2-electron oxidoreductase type, and
at least one donor for the said enzyme.
The ready-to-use dye composition in accordance with the invention leads to intense, chromatic, relatively unselective colorations with excellent properties of resistance both to atmospheric agents such as light and bad weather and to perspiration and the various treatments to which the hair may be subjected (washing, permanent-waving).
A subject of the invention is also a process for the oxidation dyeing of keratin fibres using this ready-to-use dye composition.
The 2-electron oxidoreductase(s) used in the ready-to-use dye composition in accordance with the invention can be chosen in particular from pyranose oxidases, glucose oxidases, glycerol oxidases, lactate oxidases, pyruvate oxidases and uricases.
According to the invention, the 2-electron oxidoreductase is preferably chosen from uricases of animal, microbiological or biotechnological origin.
By way of example, mention may be made of uricase extracted from boar liver, uricase from Arthrobacter globiformis, as well as uricase from Aspergillus flavus. 
The 2-electron oxidoreductase(s) can be used in pure crystalline form or in a form diluted in a diluent which is inert with respect to the said 2-electron oxidoreductase.
The 2-electron oxidoreductase(s) in accordance with the invention preferably represent(s) from 0.01 to 20% by weight approximately relative to the total weight of the ready-to-use dye composition, and even more preferably from 0.1 to 5% by weight approximately relative to this weight.
According to the invention, the term donor is understood to refer to the various substrates involved in the functioning of the said 2-electron oxidoreductase(s).
The nature of the donor (or substrate) for the said enzyme varies depending on the nature of the 2-electron oxidoreductase used. For example, as donors for the pyranose oxidases, mention may be made of D-glucose, L-sorbose and D-xylose; as a donor for the glucose oxidases, mention may be made of D-glucose; as donors for the glycerol oxidases, mention may be made of glycerol and dihydroxyacetone; as donors for the lactate oxidases, mention may be made of lactic acid and its salts; as donors for the pyruvate oxidases, mention may be made of pyruvic acid and its salts; and lastly, as donors for the uricases, mention may be made of uric acid and its salts.
The donor(s) (or substrate(s)) used in accordance with the invention preferably represent(s) from 0.01 to 20% by weight approximately relative to the total weight of the ready-to-use dye composition in accordance with the invention, and even more preferably from 0.1 to 5% by approximately relative to this weight.
The nature of the oxidation base(s) used in the ready-to-use dye composition is not a critical factor. They can be chosen, in particular, from para-phenylenediamines, double bases, para-aminophenols, ortho-aminophenols and heterocyclic oxidation bases.
Among the para-phenylenediamines which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may be made in particular of the compounds of formula (I) below, and the addition salts thereof with an acid: 
in which:
R1 represents a hydrogen atom, a C1-C4 alkyl radical, a C1-C4 monohydroxyalkyl radical, a C2-C4 polyhydroxy-alkyl radical, a (C1-C4)alkoxy(C1-C4)alkyl radical, a C1-C4 alkyl radical substituted with a nitrogenous group, a phenyl radical or a 4xe2x80x2-aminophenyl radical;
R2 represents a hydrogen atom, a C1-C4 alkyl radical, a C1-C4 monohydroxyalkyl radical, a C2-C4 polyhydroxyalkyl radical, a (C1-C4)alkoxy(C1-C4)alkyl radical or a C1-C4 alkyl radical substituted with a nitrogenous group;
R3 represents a hydrogen atom, a halogen atom such as a chlorine, bromine, iodine or fluorine atom, a C1-C4 alkyl radical, a C1-C4 monohydroxyalkyl radical, a C1-C4 hydroxyalkoxy radical, an acetylamino(C1-C4)alkoxy radical, a C1-C4 mesylaminoalkoxy radical or a carbamoylamino(C1-C4)alkoxy radical,
R4 represents a hydrogen or halogen atom or a C1-C4 alkyl radical.
Among the nitrogenous groups of formula (I) above, mention may be made in particular of amino, mono(C1-C4)alkylamino, di(C1-C4)alkylamino, tri(C1-C4)alkylamino, monohydroxy(C1-C4)alkylamino, imidazolinium and ammonium radicals.
Among the para-phenylenediamines of formula (I) above, mention may be made more particularly of para-phenylenediamine, para-toluylenediamine, 2-chloro-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,5-dimethyl-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine, N,N-diethyl-para-phenylenediamine, N,N-dipropyl-para-phenylenediamine, 4-amino-N,N-diethyl-3-methylaniline, N,N-bis(xcex2-hydroxyethyl)-para-phenylenediamine, 4-amino-N,N-bis(xcex2-hydroxyethyl)-2-methylaniline, 4-amino-2-chloro-N,N-bis(xcex2-hydroxyethyl)aniline, 2-xcex2-hydroxyethyl-para-phenylenediamine, 2-fluoro-para-phenylenediamine, 2-isopropyl-para-phenylenediamine, N-(xcex2-hydroxypropyl)-para-phenylenediamine, 2-hydroxy-methyl-para-phenylenediamine, N,N-dimethyl-3-methyl-para-phenylenediamine, N,N-(ethyl-xcex2-hydroxyethyl)-para-phenylenediamine, N-(xcex2,xcex3-dihydroxypropyl)-para-phenylenediamine, N-(4xe2x80x2-aminophenyl)-para-phenylenediamine, N-phenyl-para-phenylenediamine, 2-xcex2-hydroxyethyloxy-para-phenylenediamine, 2-xcex2-acetylaminoethyloxy-para-phenylenediamine and N-(xcex2-methoxyethyl)-para-phenylenediamine, and the addition salts thereof with an acid.
Among the para-phenylenediamines of formula (I) above, para-phenylenediamine, para-toluylenediamine, 2-isopropyl-para-phenylenediamine, 2-xcex2-hydroxyethyl-para-phenylenediamine, 2-xcex2-hydroxyethyloxy-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,3-dimethyl-para-phenylenediamine, N,N-bis(xcex2-hydroxyethyl)-para-phenylenediamine, 2-chloro-para-phenylenediamine and 2-xcex2-acetylaminoethyloxy-para-phenylenediamine and the addition salts thereof with an acid are most particularly preferred.
According to the invention, the term double bases is understood to refer to the compounds containing at least two aromatic rings bearing amino and/or hydroxyl groups.
Among the double bases which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may be made in particular of the compounds corresponding to formula (II) below, and the addition salts thereof with an acid: 
in which:
Z1 and Z2, which may be identical or different, represent a hydroxyl or xe2x80x94NH2 radical which may be substituted with a C1-C4 alkyl radical or with a linker arm Y;
the linker arm Y represents a linear or branched alkylene chain containing from 1 to 14 carbon atoms, which may be interrupted by or terminated with one or more nitrogenous groups and/or one or more hetero atoms such as oxygen, sulphur or nitrogen atoms, and optionally substituted with one or more hydroxyl or C1-C6 alkoxy radicals;
R5 and R6 represent a hydrogen or halogen atom, a C1-C4 alkyl radical, a C1-C4 monohydroxyalkyl radical, a C2-C4 polyhydroxyalkyl radical, a C1-C4 aminoalkyl radical or a linker arm Y;
R7, R8, R9, R10, R11 and R12, which may be identical or different, represent a hydrogen atom, a linker arm Y or a C1-C4 alkyl radical;
it being understood that the compounds of formula (II) contain only one linker arm Y per molecule.
Among the nitrogenous groups of formula (II) above, mention may be made in particular of amino, mono (C1-C4)alkylamino, di(C1-C4)alkylamino, tri(C1-C4)alkylamino, monohydroxy(C1-C4)alkylamino, imidazolinium and ammonium radicals.
Among the double bases of formula (II) above, mention may be made more particularly of N,Nxe2x80x2-bis-(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4xe2x80x2-aminophenyl)-1,3-diaminopropanol, N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4xe2x80x2-amino-phenyl)ethylenediamine, N,Nxe2x80x2-bis(4-aminophenyl)tetramethylenediamine, N,Nxe2x80x2-bis(xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4-aminophenyl)tetramethylenediamine, N,Nxe2x80x2-bis(4-methylaminophenyl)tetramethylenediamine, N,Nxe2x80x2-bis(ethyl)-N,Nxe2x80x2-bis(4xe2x80x2-amino-3xe2x80x2-methylphenyl)ethylenediamine and 1,8-bis(2,5-diaminophenoxy)-3,5-dioxaoctane, and the addition salts thereof with an acid.
Among these double bases of formula (II), N,Nxe2x80x2-bis (xcex2-hydroxyethyl)-N,Nxe2x80x2-bis(4xe2x80x2,-aminophenyl)-1,3-diaminopropanol and 1,8-bis(2,5-diaminophenoxy)-3,5-dioxaoctane, or one of the addition salts thereof with an acid, are particularly preferred.
Among the para-aminophenols which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may be made in particular of the compounds corresponding to formula (III) below, and the addition salts thereof with an acid: 
in which:
R13 represents a hydrogen or halogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, (C1-C4)alkoxy(C1-C4)alkyl, C1-C4 aminoalkyl or hydroxy(C1-C4)alkylamino(C1-C4)alkyl radical,
R14 represents a hydrogen or halogen atom or a C1-C4 alkyl, C1-C4 monohydroxyalkyl, C2-C4 polyhydroxyalkyl, C1-C4 aminoalkyl, C1-C4 cyanoalkyl or (C1-C4)alkoxy(C1-C4)alkyl radical,
it being understood that at least one of the radicals R13 or R14 represents a hydrogen atom.
Among the para-aminophenols of formula (III) above, mention may be made more particularly of para-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol, 4-amino-3-hydroxymethylphenol, 4-amino-2-methylphenol, 4-amino-2-hydroxymethylphenol, 4-amino-2-methoxymethylphenol, 4-amino-2-aminomethylphenol, 4-amino-2-(xcex2-hydroxyethylaminomethyl)phenol and 4-amino-2-fluorophenol, and the addition salts thereof with an acid.
Among the ortho-aminophenols which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may be made more particularly of 2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol and 5-acetamido-2-aminophenol, and the addition salts thereof with an acid.
Among the heterocyclic bases which can be used as oxidation bases in the dye compositions in accordance with the invention, mention may be made more particularly of pyridine derivatives, pyrimidine derivatives, pyrazole derivatives and pyrazolopyrimidine derivatives, and the addition salts thereof with an acid.
Among the pyridine derivatives, mention may be made more particularly of the compounds described, for example, in patents GB 1,026,978 and GB 1,153,196, such as 2,5-diaminopyridine, 2-(4-methoxyphenyl)amino-3-aminopyridine, 2,3-diamino-6-methoxypyridine, 2-(xcex2-methoxyethyl)amino-3-amino-6-methoxypyridine and 3,4-diaminopyridine, and the addition salts thereof with an acid.
Among the pyrimidine derivatives, mention may be made more particularly of the compounds described, for example, in German patent DE 2,359,399 or Japanese patents JP 88-169,571 and JP 91-10659 or patent applications WO 96/15765, such as 2,4,5,6-tetraaminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine, 2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidine and 2,5,6-triaminopyrimidine, and the addition salts thereof with an acid.
Among the pyrazole derivatives, mention may be made more particularly of the compounds described in patents DE 3,843,892, DE 4,133,957 and patent applications WO 94/08969, WO 94/08970, FR-A-2,733,749 and DE 195 43 988, such as 4,5-diamino-1-methylpyrazole, 3,4-diaminopyrazole, 4,5-diamino-1-(4xe2x80x2-chlorobenzyl)pyrazole, 4,5-diamino-1,3-dimethylpyrazole, 4,5-diamino-3-methyl-1-phenylpyrazole, 4,5-diamino-1-methyl-3-phenylpyrazole, 4-amino-1,3-di-methyl-5-hydrazinopyrazole, 1-benzyl-4,5-diamino-3-methylpyrazole, 4,5-diamino-3-tert-butyl-1-methylpyrazole, 4,5-diamino-1-tert-butyl-3-methylpyrazole, 4,5-diamino-1-(xcex2-hydroxyethyl)-3-methylpyrazole, 4,5-diamino-1-ethyl-3-methylpyrazole, 4,5-diamino-1-ethyl-3-(4xe2x80x2-methoxyphenyl)pyrazole, 4,5-diamino-1-ethyl-3-hydroxymethylpyrazole, 4,5-diamino-3-hydroxymethyl-1-methylpyrazole, 4,5-diamino-3-hydroxymethyl-1-isopropylpyrazole, 4,5-diamino-3-methyl-1-isopropylpyrazole, 4-amino-5-(2xe2x80x2-amino-ethyl)amino-1,3-dimethylpyrazole, 3,4,5-triaminopyrazole, 1-methyl-3,4,5-triaminopyrazole, 3,5-diamino-1-methyl-4-methylaminopyrazole and 3,5-diamino-4-(xcex2-hydroxyethyl)amino-1-methylpyrazole, and the addition salts thereof with an acid.
Among the pyrazolopyrimidine derivatives, mention may be made more particularly of the pyrazolo[1,5-a]pyrimidines of formula (IV) below, and the addition salts thereof with an acid or with a base and the tautomeric forms thereof, when a tautomeric equilibrium exists: 
in which:
R15, R16, R17 and R18, which may be identical or different, denote a hydrogen atom, a C1-C4 alkyl radical, an aryl radial, a C1-C4 hydroxyalkyl radical, a C2-C4 polyhydroxyalkyl radical, a (C1-C4)alkoxy(C1-C4)alkyl radical, a C1-C4 aminoalkyl radical (it being possible for the amine to be protected with an acetyl, ureido or sulphonyl radical), a (C1-C4)alkylamino(C1-C4)alkyl radical, a di[(C1-C4)alkyl]amino(C1-C4)alkyl radical (it being possible for the dialkyl radicals to form a 5- or 6-membered carbon-based ring or a heterocycle), a hydroxy(C1-C4)alkyl- or di[hydroxy(C1-C4)alkyl]amino(C1-C4)alkyl radical;
the radicals X, which may be identical or different, denote a hydrogen atom, a C1-C4 alkyl radical, an aryl radical, a C1-C4 hydroxyalkyl radical, a C2-C4 polyhydroxyalkyl radical, a C1-C4 aminoalkyl radical, a (C1-C4)alkylamino(C1-C4)alkyl radical, a di[(C1-C4)alkyl]amino(C1-C4)alkyl radical (it being possible for the dialkyls to form a 5- or 6-membered carbon-based ring or a heterocycle), a hydroxy(C1-C4)alkyl- or di-[hydroxy(C1-C4)alkyl]amino(C1-C4)alkyl radical, an amino radical, a (C1-C4)alkyl- or di[(C1-C4)alkyl]amino radical; a halogen atom, a carboxylic acid group, a sulphonic acid group;
i is equal to 0, 1, 2 or 3;
p is equal to 0 or 1;
q is equal to 0 or 1;
n is equal to 0 or 1;
with the proviso that:
the sum p+q is other than 0;
when p+q is equal to 2, then n is equal to 0 and the groups NR15R16 and NR17R18 occupy the (2,3); (5,6); (6,7); (3,5) or (3,7) positions;
when p+q is equal to 1, then n is equal to 1 and the group NR15R16 (or NR17R18) and the OH group occupy the (2,3); (5,6); (6,7); (3,5) or (3,7) positions.
When the pyrazolo[1,5-a]pyrimidines of formula (IV) above are such that they contain a hydroxyl group on one of the positions 2, 5 or 7 xcex1 to a nitrogen atom, a tautomeric equilibrium exists represented, for example, by the following scheme: 
Among the pyrazolo[1,5-a]pyrimidines of formula (IV) above, mention may be made in particular of:
pyrazolo[1,5-a]pyrimidine-3,7-diamine;
2,5-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;
pyrazolo[1,5-a]pyrimidine-3,5-diamine;
2,7-dimethylpyrazolo[1,5-a]pyrimidine-3,5-diamine;
3-aminopyrazolo[1,5-a]pyrimidin-7-ol;
3-aminopyrazolo[1,5-a]pyrimidin-5-ol;
2-(3-aminopyrazolo[1,5-a]pyrimidin-7-ylamino)ethanol;
2-(7-aminopyrazolo[1,5-a]pyrimidin-3-ylamino)ethanol;
2-[(3-aminopyrazolo[1,5-a]pyrimidin-7-yl)-(2-hydroxyethyl)amino]ethanol;
2-[(7-aminopyrazolo[1,5-a]pyrimidin-3-yl)-(2-hydroxyethyl)amino]ethanol;
5,6-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;
2,6-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;
2,5,N7,N7-tetramethylpyrazolo[1,5-a]pyrimidine-3,7-diamine;
and the addition salts thereof and the tautomeric forms thereof, when a tautomeric equilibrium exists.
The pyrazolo[1,5-a]pyrimidines of formula (IV) above can be prepared by cyclization starting with an aminopyrazole, according to the syntheses described in the following references:
EP 628559 Beiersdorf-Lilly.
R. Vishdu, H. Navedul, Indian J. Chem., 34b (6), 514, 1995.
N. S. Ibrahim, K. U. Sadek, F. A. Abdel-Al, Arch. Pharm., 320, 240, 1987.
R. H. Springer, M. B. Scholten, D. E. O""Brien, T. Novinson, J. P. Miller, R. K. Robins, J. Med. Chem., 25, 235, 1982.
T. Novinson, R. K. Robins, T. R. Matthews, J. Med. Chem., 20, 296, 1977.
U.S. Pat. No. 3,907,799 ICN Pharmaceuticals.
The pyrazolo[1,5-a]pyrimidines of formula (IV) above can also be prepared by cyclization starting from hydrazine, according to the syntheses described in the following references:
A. McKillop and R. J. Kobilecki, Heterocycles, 6(9), 1355, 1977.
E. Alcade, J. De Mendoza, J. M. Marcia-Marquina, C. Almera, J. Elguero, J. Heterocyclic Chem., 11(3), 423, 1974.
K. Saito, I. Hori, M. Higarashi, H. Midorikawa, Bull. Chem. Soc. Japan, 47(2), 476, 1974.
The oxidation base(s) preferably represent(s) from 0.0005 to 12% by weight approximately relative to the total weight of the dye composition in accordance with the invention, and even more preferably from 0.005 to 6% by weight approximately relative to this weight.
The ready-to-use dye composition in accordance with the invention can also contain one or more couplers. These couplers can be chosen in particular from meta-phenylenediamines, meta-aminophenols, meta-diphenols, heterocyclic couplers such as, for example, indole derivatives, indoline derivatives, benzimidazole derivatives, benzomorpholine derivatives, sesamol derivatives and pyridine, pyrimidine and pyrazole derivatives, and the addition salts thereof with an acid.
These couplers are chosen more particularly from 2-methyl-5-aminophenol, 5-N-(xcex2-hydroxyethyl)amino-2-methylphenol, 3-aminophenol, 1,3-dihydroxybenzene, 1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene, 2,4-diamino-1-(xcex2-hydroxyethyloxy)benzene, 2-amino-4-(xcex2-hydroxyethylamino)-1-methoxybenzene, 1,3-diaminobenzene, 1,3-bis(2,4-diaminophenoxy)propane, sesamol, xcex1-naphthol, 6-hydroxyindole, 4-hydroxyindole, 4-hydroxy-N-methylindole, 6-hydroxyindoline, 2,6-dihydroxy-4-methylpyridine, 1-H-3-methylpyrazol-5-one and 1-phenyl-3-methyl pyrazole-5-one, and the addition salts thereof with an acid.
When they are present, the coupler(s) preferably represent(s) from 0.0001 to 10% by weight approximately relative to the total weight of the ready-to-use dye composition, and even more preferably from 0.005 to 5% by weight approximately relative to this weight.
In general, the addition salts with an acid which can be used in the context of the dye compositions of the invention (oxidation bases and couplers) are chosen in particular from the hydrochlorides, hydrobromides, sulphates, tartrates, lactates and acetates.
The C4-C8 ether(s) of a C2 glycol used in the ready-to-use dye composition in accordance with the invention is (are) preferably chosen from C4-C8 alkyl ethers of a C2 glycol, such as ethylene glycol monobutyl ether and C6-C8 aryl ethers of a C2 glycol, such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
The C1-C8 ether(s) of a C3-C9 glycol used in the ready-to-use dye composition in accordance with the invention is (are) preferably chosen from C1-C8 alkyl ethers of a C3-C9 glycol, such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, isopropylene glycol dimethyl ether, diethylene glycol monomethyl ether and monoethyl ether, dipropylene glycol monomethyl ether and tripropylene glycol monomethyl ether, and C6-C8 aryl ethers of a C3-C9 glycol, such as propylene glycol monophenyl ether, propylene glycol monobenzyl ether, diethylene glycol monophenyl ether and diethylene glycol monobenzyl ether.
The C4-C8 ether(s) of a C2 glycol and/or the C1-C8 ether(s) of a C3-C9 glycol preferably represent(s) from 1 to 40% by weight approximately relative to the total weight of the ready-to-use dye composition according to the invention, and even more preferably from 5 to 30% by weight approximately relative to this weight.
The ready-to-use dye composition in accordance with the invention can also contain one or more direct dyes, in particular in order to modify the shades or to enrich them with glints.
The medium which is suitable for dyeing (or support) for the ready-to-use dye composition in accordance with the invention generally consists of water. The medium which is suitable for dyeing may also contain one or more solvents other than C4-C8 ethers of a C2 glycol and C1-C8 ethers of a C3-C9 glycol of the invention.
The pH of the ready-to-use composition in accordance with the invention is chosen such that the enzymatic activity of the 2-electron oxidoreductase is sufficient. It is generally between 5 and 11 approximately, and preferably between 6.5 and 10 approximately. It can be adjusted to the desired value using acidifying or basifying agents usually used for dyeing keratin fibres.
Among the acidifying agents, mention may be made, by way of example, of inorganic or organic acids such as hydrochloric acid, orthophosphoric acid, sulphuric acid, carboxylic acids such as acetic acid, tartaric acid, citric acid or lactic acid, and sulphonic acids.
Among the basifying agents, mention may be made, by way of example, of aqueous ammonia, alkaline carbonates, alkanolamines such as mono-, di- and triethanolamines, 2-methyl-2-aminopropanol and derivatives thereof, sodium hydroxide, potassium hydroxide and the compounds of formula (V) below: 
in which W is a propylene residue optionally substituted with a hydroxyl group or a C1-C4 alkyl radical; R19, R20, R21 and R22, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl or C1-C4 hydroxyalkyl radical.
The ready-to-use dye composition in accordance with the invention can also contain various adjuvants used conventionally in compositions for the dyeing of the hair, such as anionic, cationic, nonionic, amphoteric or zwitterionic surfactants or mixtures thereof, anionic, cationic, nonionic, amphoteric or zwitterionic polymers or mixtures thereof, inorganic or organic thickeners, antioxidants, enzymes other than the 2-electron oxidoreductases used in accordance with the invention, such as, for example, peroxidases, penetration agents, sequestering agents, fragrances, buffers, dispersing agents, conditioners such as, for example, silicones which may or may not be volatile or modified, film-forming-agents, ceramides, preserving agents and opacifiers.
Needless to say, a person skilled in the art will take care to select this or these optional complementary compound(s) such that the advantageous properties intrinsically associated with the ready-to-use dye composition in accordance with the invention are not, or are not substantially, adversely affected by the addition or additions envisaged.
The ready-to-use dye composition in accordance with the invention can be in various forms, such as in the form of liquids, creams or gels, which may be pressurized, or in any other form which is suitable for dyeing keratin fibres, and in particular human hair. In this case the oxidation dye(s) and the 2-electron oxidoreductase(s) are present in the same ready-to-use composition, and consequently the said composition must be free of gaseous oxygen, so as to avoid any premature oxidation of the oxidation dye(s).
A subject of the invention is also a process for dyeing keratin fibres, and in particular human keratin fibres such as the hair, using the ready-to-use dye composition as defined above.
According to this process, at least one ready-to-use dye composition as defined above is applied to the fibres, for a period which is sufficient to develop the desired coloration, after which the fibres are rinsed, optionally washed with shampoo, rinsed again and dried.
The time required to develop the coloration on the keratin fibres is usually between 3 and 60 minutes and even more precisely between 5 and 40 minutes.
According to one first specific embodiment of the invention, the process includes a preliminary step which consists in separately storing, on the one hand, a composition (A1) comprising, in a medium which is suitable for dyeing, at least one oxidation base and at least one C4-C8 ether of a C2 glycol and/or at least one C1-C8 ether of a C3-C9 glycol, and, on the other hand, a composition (B1) comprising, in a medium which is suitable for dyeing, at least one enzyme of 2-electron oxidoreductase type in the presence of at least one donor for the said enzyme, and then in mixing them together at the time of use, after which this mixture is applied to the keratin fibres.
According to a second specific embodiment of the invention the process includes a first step which consists in separately storing, on the one hand, a composition (A2) comprising, in a medium which is suitable for dyeing, at least one oxidation base, and, on the other hand, a composition (B2) containing, in a medium which is suitable for dyeing, at least one C4-C8 ether of a C2 glycol and/or at least one C1-C8 ether of a C3-C9 glycol, and at least one enzyme of 2-electron oxidoreductase type in the presence of at least one donor for the said enzyme, followed by mixing them together at the time of use, after which this mixture is applied to the keratin fibres.
Another subject of the invention is a multi-compartment dyeing device or xe2x80x9ckitxe2x80x9d or any other multi-compartment packaging system, a first compartment of which comprises composition (A1) or (A2) as defined above and a second compartment of which comprises composition (B1) or (B2) as defined above. These devices can be equipped with means for delivering the desired mixture onto the hair, such as the devices described in patent FR-2,586,913 in the name of the Applicant.
The examples which follow are intended to illustrate the invention without, however, limiting its scope.